The efficient analysis of a number of samples through nuclear magnetic resonance (NMR) has been the subject of development over the course of many years. One major limit to throughput is the physical insertion and removal of samples from the sensitive region of the apparatus. Prior art has been directed to placement of a number of samples within the bore of the NMR magnet with suitable mechanical conveyance of a sample into the sensitive volume for measurement with subsequent removal and advancement of the next sample into the sensitive volume. These arrangements increase throughput by minimizing the time required for the placement and removal of samples and simplification of the sample handling operations. Examples are U.S. Pat. No. 6,414,491 and U.S. Pat. No. 6,768,305, both commonly assigned herewith. Additionally, certain complex experiments, such as those requiring temperature regulation at non-ambient conditions, have exploited an overlap of measurement of the instant sample with temperature preparation of the next sample(s) as described in U.S. Pat. No. 6,768,305. The latter is an example of the concurrence of steps required for different samples.
It is also known in prior art to employ differential pressure control for a sample conduit to accurately position individual samples within the sample volume. In this art, both ends of the sample conduit are pressurized with an inert gas and pressure regulation is available at both ends whereby the pressure differential is controlled in magnitude and sign. Discrete samples are precisely positioned using the differential pressure in combination with processing of the NMR signal from the sample to optimize that signal in respect to sample position, as described by U.S. Pat. No. 5,705,928 commonly assigned herewith and incorporated by reference.
It is known in prior art to rapidly transport a particular sample for analysis from one magnetic field region of an NMR magnet (high field) to another region (low field) for certain types of experiments. Sample shuttles for such physical transfer are well known. This is done cyclically for the purposes of the specific analytic process directed to the particular sample. An example of this is described by Redfield, http://www.bio.brandeis.edu/faculty01/redfield/shuttleIII.pdf,May15,2000.
Prior art approaches to increasing sample throughput contemplate multiplexing of apparatus, such as multiple RF resonators. Coupling between different sample channels presents problems, particularly because of concurrent process steps occurring in close physical proximity. Multiple independent and quasi-independent channels with duplicate hardware present considerable complexity in operation and calibration. In such apparatus, it is apparent that the several samples are subject to measurements in different regions of the magnetic field, in proximity to different sources of transient disturbances, and within different resonator structures.
It is conventional for NMR measurements to be repeated a sufficient number of times to complete an averaging process. Such averaging is often required to enhance (coherent) true signal with respect to (incoherent) noise. In other types of experiment, a substantial time delay is an integral step of the particular pulse sequence defining the measurement. Heretofore, whether an integral portion of a pulse sequence or the interval between repetitions, these delays have been regarded as an irreducible component of experiment throughput.